1. Field of the Invention
This invention relates to a heater with solid electrolyte, and more particularly to a ceramic heater having an excellent durability at high temperatures.
2. Description of the Prior Art
A ceramic heater comprising an electric resistor gastightly sealed in a ceramic insulator, such as a tungsten wire gastightly sealed in an alumina ceramics, has been known.
The ceramic heater of the prior art has a shortcoming in that the practicable highest temperature at which the ceramic heater can be used is limited to a comparatively low level of about 800.degree. C. at most, because when the temperature of ceramics forming the insulator thereof is raised, the insulation of the ceramics is reduced and oxygen diffusion tends to occur through the ceramics.